Blood pumps are devices which are used to assist the heart of a mammalian subject such as a human patient. One type of blood pump known to those of skill in the art is a ventricular assist device (“VAD”). A VAD may include a pump which is implanted in the body of the subject (e.g., a human patient). The term “implanted” is given its art recognized meaning and the pumps described herein are sized and shaped in accordance with the requirements of the subject. The pump typically has an inlet connected to a source of blood to be circulated, and an outlet connected to an artery. Most typically, the inlet of the pump is connected to the interior of the left ventricle and the outlet of the pump is connected to the aorta, so that the pump operates in parallel with the left ventricle to impel blood into the aorta. The pump may be a miniature rotary impeller pump having an impeller disposed in a pump housing and driven in rotation by a small electric motor that may be closely integrated with the pump. The motor in turn typically is powered by an implantable power source such as a storage battery with an arrangement for charging the battery from an external power source. The VAD may also include a control system which controls operation of the power source so as to drive the impeller at a set rotational speed and thus provide constant pumping action.
Blood pumps can be used to assist the heart of subjects suffering from conditions which impair the pumping ability of the heart. Such assistance can be provided permanently, or while the subject awaits a suitable heart implanted in accordance with its art recognized meaning, sized and shaped. In other cases, the assistance provided by the VAD allows the heart to heal.